One of the problems with late model American cars, which may be related to the use of unleaded gasoline, is the contamination of the gas tank with impurities. The problem often is so serious as to require removal of the gas tank from the car and steam-cleaning of its interior, followed by re-attachment of the gas tank to the car. This is a time consuming and expensive procedure.
The same problem of keeping the fuel tank clean exists with power boats, also.
Prior to the present invention there have been various proposals for recirculating oil or the like through a pump and a filter to keep it clean. Examples of such prior arrangements are disclosed in the following U.S. Pat. Nos.: Vokes, 2,499,705; Busby, 2,685,347; and Vawter, 2,425,848. However, such prior proposals were not adapted for cleaning fuel tanks on cars and power boats.